Classification and characterisation of crude oils based on distillation properties

True boiling point (TBP) distillation is a widely used batch distillation process for the characterisation of crude oils, traditionally mainly for marketing and refining purposes. The TBP curve is obtained by plotting the cumulative mass or volume distillation fraction with increasing temperature. The shape of these curves is dependent on the volatility of components in a given crude oil. As such, these curves give a “footprint” of the composition of crude oils.A new method of characterising crude oils based on the shape of TBP distillation curves is proposed. A gamma distribution is used to characterise the TBP distillation curve, and the parameters of the fitted distribution are used as characterisation parameters. The proposed method is found to describe experimental data very well with just two parameters, and as such offers a very practical approach in terms of classifying crude oils. Ranges of values for the characterisation parameters for different types of crude oil are identified for a large set of TBP data. The characterisation parameters can be correlated with a number of crude oil properties. They can also be used to predict the petroleum fractions that can be produced from a given crude oil and hence correlated to the value of that crude.As an alternative, it is shown how crude oil cut fractions may be classified with the aid of a ternary diagram, and the link between this approach and the characterisation parameters introduced above is demonstrated.